Gromphadorhina oblongonota, commonly known as the wide-horned hissing cockroach, is a massive, flightless insect native exclusively to southern Madagascar. It is recognized as one of the largest cockroach species in the world. Adults routinely reach lengths between 8 to 10 centimetres (over 3 to 4 inches).
 
Key Characteristics
Appearance: They feature a glossy, deep burgundy-to-black abdomen. Mature males possess incredibly prominent, wide bumps or "horns" on their pronotum (the shield-like structure behind the head).
The Hiss: Like other members of its genus, it expels air through its respiratory spiracles to produce a loud hiss. This serves to ward off potential predators or establish dominance during male-to-male combat.
Behavior: They are nocturnal detritivores. In the wild, they occupy forest floors, rotting logs, and leaf litter to recycle decaying organic material.
 
The Pet Trade and Common Confusion
Because they are docile and live for 2 to 3 years, they are popular in the exotic pet hobby. They are frequently confused or cross-bred with the standard Madagascar hissing cockroach (Gromphadorhina portentosa). However, G. oblongonota is significantly larger, darker, and features much wider male pronotal horns.
 
Captive Care Baselines
Enclosure: A well-ventilated terrarium with secure, climb-proof barriers is necessary.
Temperature & Humidity: They thrive in warm environments above 20°C (ideally 24°C–28°C) with moderate to high humidity. Keeping temperatures on the lower end can slow down their prolific breeding cycles.
Diet: A varied diet consisting of fresh fruits and vegetables (like carrots, sweet potatoes, and zucchini) supplemented with a dry protein source (such as dog food or fish flakes).